For men with liver disease and low testosterone, taking testosterone therapy for a year can help them gain about 1.7 kg more muscle in their arms and legs compared to not taking it.

For men with liver disease and low testosterone, taking testosterone therapy for a year helps them gain muscle and lose fat, making their body composition healthier.

Giving testosterone to men with liver disease and low testosterone levels might help strengthen their bones a little bit over a year, making them less likely to break.

For men with liver disease and low testosterone, giving them testosterone shots or pills can raise their blood’s hemoglobin levels by about 10 points over a year, which might help fix their anemia.

If young men eat much less and exercise a lot for four weeks while taking a high dose of testosterone, they gain a few extra kilograms of muscle compared to those taking a fake pill—even though their strength and leg function don’t get better.

Taking a lot more testosterone than your body normally makes—without working out—can make your muscles bigger and add about 7 pounds of muscle mass, showing that testosterone alone can build muscle.